Corrosionproof liner



Feb 15, 1943- R. M. THOMAS ETAL 2,311,308

coRRosIoN-PROOF LINER I Filed Dec. 30, 1938 2 Sheets-Sheet l Feb. 16,1943. R. THOMAS ETAL 2,311,308

CORROSION-PROOF LINER Filed Dec. 30, 1938 2 Sheets-Sheet 2 7 o1. v/vnsamaare-1 AFTAER 10D/YS /4/ CQNCENTRATED .SQLPHURIQ fic/.v

Patented Feb. 16, 1943 UNITED STATES PATENT OFFIC ooanoslomoor LINERnobel-1 M. Thomas. Union, and william J. sparks,

@nuten-d, N. J., assiznors to Jacco, Incorporated, a corporation ofLouisiana Application December 30, 1938, Serial No. 248,526

Claims.

This invention relates to containers, and particularlyto containershaving a corrosion-proof lining which is resistant to acids, alkalis,oxygencontaining and water-soluble substances generally; and relatesespecially to a container having a lining of a polymer substance made upci' isobutyiene and butadiene polymerized together.

The problem of containers, ducts and handling equipment for corrosivefluids has been one of the most diflicult which the chemist has beencalled upon to solve.' The problem of large containers, such as tanksand particularly large portable containers such as tank cars, for hold-`ing corrosive liquids such as strong sulfuric, hydrochloric and nitricacids, as well as the weaker acids and alkalis, has proven to beparticularly dimcult since none of the metals are fully resistant toconcentrated sulfuric or concentrated nitric acid, nor to strong causticsolution, and accordingly a metal container contaminates the containedliquids in a very short time, and the container itself is destroyed orpunctured in a relatively short time. Attempts have been made to linetanks with various resistant materials such as rubber, glassI variousenamels, etc., but to the present without entire success. This is due tothe fact that linings such as glass, when applied to a steel container,chip oil and break away from the container under such inuenees asvibration and temperature changes, and the smallest puncture in theglass lining results in immediate contamination oi the contained fluid,and an early failure of the container by puncture of the metal wall.Rubber linings in` such containers do not at all withstand the attacksof acid, and especially with stronger nitric and sulfuric acids, thedeterioration is exceedingly rapid to failure within relatively iewhours, making the liner useless for such strong acids.

The present invention provides a new and useful lining material whichhas the unexpected combination of properties of being wholly resistantto any concentration of any of the acids (or alkalis); of being elastic,flexible, and of high abrasion resistance and high ilexure capacity; andthe further property of being readily bonded to metal surfaces. Thismaterial is a. polymer substance made up of from 70% to 90% isobutyleneand 30% to 10% of butadiene, polymerized together at low temperature toproduce a high molecular weight polymer, and compounded with appropriateiillers and other substances.

Thus the invention consists of `a container or duct having a compoundedoleiinic polymer subto protect a corrodible body by the applicationthereto of a polymerized oleflnic substance: which substance desirablyconsists of a high molecular weight linear polymer made up ofisobutylene and butadiene; which polymer desirably contains in additionvarious compounding substances; and provides a high resistance to acidsand alkalis, high elasticity and high abrasion and flexure resistance.

This application is a continuation in part of our copending application,Serial No. 182,252, nled December 29, lil-37. v

Other objects and structural details will be apparent from the followingdescription when read in connection with the accompanying drawingswherein Fig. i. is a view in cross section of a duct structure having alining according to the invention;

Fig. 2 is a perspective view partly in section of a portable containerstructure according to the invention;

Fig. 3 is a perspective view partly in section of a iixed containerstructure according to the device oi the invention;

Fig. 4 is a perspective view partly in section of a small container forcomestibles according to the invention;

Fig. 5 is a view of comparative test experiments on rubber and thepolymer substance before and after submergence for 20 hours inconcentrated nitric acid; and

Fig. 6 is a similar View of comparative test experiments on rubber andthe polymer substance before and after submergence for 10 days inconcentrated sulfuric acid.

In the preparation' of the structure of the invention, the linermaterial is conveniently produced from waste gases resulting from thecracking of petroleum hydrocarbons. As is well known, crude petroleum istopped for gasoline and fractionated to separate a cracking stock, whichis cracked at high pressure and temperature to convert a substantialportion into gasoline boiling range hydrocarbons. About 15% of thecracking oil leaves the process in the formof4 gases consisting ofhydrogen; substantial amounts of the lower saturated hydrocarbons of themethane series; substantial quantities of the ethylene series ofunsaturated hydrocarbons, and smaller quantities of other unsaturatedcompounds. 'Ihis mixture is fractionated to separate the isobutylene andthe butadiene, from the mixture. These two gases are then mixed in theproportion of from 70 parts to 90 parts of stance lining; and an objectof the invention is isobutylene with 301291118 t0 10 Darts 0f butadiene.

ride dissolved in ethyl chloride, or titanium tetrachloride or borontrifiuoride, at temperatures below C., preferably at temperaturesranging from 50 C. to l50 C. At these temperatures a rapidpolymerization reaction occurs to produce a solid polymer substancewhich has relatively very few unsaturated bonds between carbon atoms,shown by-.the low iodine number. The'resulting polymer is freed from thecatalyst and may be subjected to other purification steps if desired. Atroom temperature it is a solid, with an elasticity and elongationcomparable to that of rubber. It is, however, chemically very differentfrom rubber, because of the relatively high degree of chemicalsaturation as compared to rubber.

lThe material will. however, combine' with sulfur. in whichcharacteristic it is sharply different from simple polyisobutylene; Theamount of sulfur which can be combined into the molecules of the polymersubstance is, however, relatively small, and when this small amount ofsulfur has been combined, the material is still more highly resistant tooxidation, and still more highly resistant to acids or alkalis of anyform. Moreover, when sulfur is combined into the polymer to thesaturation point, it retains its elongation and elasticity, in sharpcontrast to rubber, which when fully saturated with sulfur is a hard,.brittle substance. Furthermore, it has a chemicalinertness which is ofa wholly different order of magnitude from that of rubber.

This characteristic property is indicated in Figs. and 6. Fig. 5 showssamples of the sulfurized polymer substance before and after twentyhours exposure submerged in strong nitric acid at room temperature. Itshows that no perceptible attack has occurred from the nitric acid onthe polymer substance. In fact weeks.

and even months, of contact with nitric acid produce no perceptiblereaction by the acid upon the polymer substance. In contrast to this asshown in Fig. 5, vulcanized rubber is completely disintegrated byconcentrated nitric acid in the course of twenty hours' exposure. Thatis, twothirds to three-fourths of the rubber material is dissolved inthe nitric acid, and the small amount of insoluble material remains asmerely a small amount of debris. Similarly in Fig. 6, the copolymermaterial is wholly resistant to concentrated sulfuric acid, whereas, asshown. rubber is charred, swollen. and generally. disintegrated by tendays immersion in the concentrated sulfuric acid.

The polymer material is desirably compounded according to the followingformula:

Isobutylene, 80% 100 Butadiene, Clay 5 Captax 3 Zimate 1 Agerite powder1 sulfur 4 l Stearic acid 4 It will be observed that the four parts ofsulfur per hundred of polymer substance substantially completelysaturates the material chemically, and contributes markedly to itschemical resistivity. It is further to be observed, however, that thiscondition of chemical saturation does not inJure the flexibility orelasticity of the material and does not inJure any of its advantageousand abrasion resistance of the material, still further increases itschemical resistivity to attack by the various reagents, increases itselongation and reduces any tendencies towards tacklness or cold flow.

(The "Captax" mentioned in the above formula is mercapto benzo thiazolewhich aids and facilitates the sulfurization. The "Zimate" mentioned iszinc dimethyl-dithiocarbamate .which still further aids'thesulfurization. The

Agerite Powder is phenyl B `naphthylamine which'stabilizes the materialagainst temperature reactions.)

The material may be sheeted out upon a roll mill after the compounding.and ymay be applied to the interior of the container in the form ofsheets which are caused to become adherent to the metal of the containerby the preliminary application to the surface of the container of a thinlayer of the compounded polymer dissolved in a suitable solvent such asa light hydrocarbon or chlorinated hydrocarbon. The compounded polymermaterial in sheet form may then be applied to the surface of thecontainer after the solvent has substantially evaporated from the firstlayer. The Joints between successive strips of the polymer material maybe closed by the application of material in solution, or by working theedges together with a roller in a manner closely analogous to that usedfor wallpaper. When the lining is completed, the container may beheated, preferably under pressure. to a temperature in the neighborhoodof C. to C. for a period of about one hour which is sufiicient to causethe combination of the sulfur with the polymer to build up to themaximum its chemically resistant properties.

Alternatively, the compounded polymer material may be sheeted out andsulfurized in the sheet form preparatory to application to thecontainer.

This is particularly convenient for the embodi- Vment of Fig. 1 wherethe polymer material I is conveniently produced in tube form asindicated. The polymer material may conveniently be extruded, by the aidof a press, to form the desired tube, or it may be prepared by wrappingsheets of the material around a collapsible mandril. The metal duct orconveyor 2 is desirably treated on its inner surface with a thin layerof the compounded polymer substance in solvent to form an adhesive lm I.When the film of compounded polymer substance within the tube issubstantially dry, the polymer material may be drawn into place in thetube. It may conveniently be extruded with a diameter considerably lessthan the internal diameter of the tube, and after being drawn into thetube it may be expanded by air or steam or water pressure within thetube until firm contact is made with the interior wall of the tube. Ifdesired, the film may be converted into similar material to the fullyresistant liner II by the application of hea-t as above pointed out.When so treated the lining polymer material l is firmly held to themetal portion 2.

The embodiments of Fig. 2 and Fig. 3 may conveniently be produced byfabrication of the material into the desired tank structures l and l,and the incorporation thereinto of the polymer material linings 5 and 1by either of the methods above pointed out. In either event the polymerThe embodiment of Fig.l l is particularly desirable as a duct for theconveyance of powerfully corrosive liquids either acid or alkaline. Theembodiment of Fig. 2 is particularly desirable for the shipment ofpowerfully corrosive liquids either acid or alkaline; and the embodimentof Fig. 3 is particularly desirable for the storage of such liquids.

It will be noted that the above presented formula for compounding thepolymer material includes a small portion of clay. This is presented asa typical inert filler and it may be present in proportions ranging froml or 2 parts per hundred of polymer to amounts as high as 200 parts perhundred of polymer depending upon the particular substance chosen toserve as the inert filler. In addition to clay. carbon black is a highlyadvantageous filler material as is also barytes. Zinc oxide is usefulfor some purposes, but it is not fully suitable for all corrosiveliquids. When strong nitric, sulfuric or hydrochloric acids are to be incontact with the polymer lining, zinc oxide is less satisfactory, sinceit shows some tendency to reduce the inertness of the compoundedpolymer. F'or the mild acids, and for alkalis, zinc oxide is asatisfactory inert filler as are also magnesium oxide and similarsubstances.

In some instances it is desired to package small amounts oi' substancessuch as small amounts of The above-described embodiment suggests onlythe lining oi the container with polymer. It is, however, readilypossible to cover the container `both inside and outside withV thepolymer material, thereby dispensing entirely with the use of tin Aas arust preventive. Furthermore, the polymer is transparent, especially inthin layers, and the desired label and other marks may be printeddirectly upon the metal of the container, and covered by the exteriorlayer of polymer. This embodiment is particularly advantageous, becauseof the very high strength and very high abrasion resistance of thepolymer material, which is superior to that of the ordinary coating oftin as applied to commercial tern plate.

The material is particularly advantageous for the protection of metallicstructures generally against corrosive influences from liquids, solidsand gas. It is particularly advantageous as a container for solidcaustic substances such as solid caustic soda or caustic potash, as wellas acid fruits, or small amounts of the more powerful acid and alkalineliquids. For this purpose the embodiment of Fig. 4 may be utilized. For

`rosive liquids such as nitric and sulfuric acids, the polymer substancemay be moulded by the application of a low degree of heat and pressureinto the desired form of the container and inserted therein with orwithout the intermediate presence of a layer of the polymer substancedeposited from solution. The lining may then be heated for theappropriate time to develop the complete chemical resistivity.

The container, especially for comestibles, may

be formed by the usual automatic machine process of rolling and seamingsheet iron, either with orwithout coatings of tin; and stamping andseaming to the rolled portion an appropriate bottom closure. The liningof polymer material may be applied tothe container at this stage, andmay be applied simultaneously to the appropriate surface oi a stampedcover member. The heat treatment for completing the sulfurization may beapplied to both portions of the structure after evaporation of thesolvent. The comestible may then be inserted within the bottom portion,and the top cover may thereafter be seemed to the cylindrical portion byfolding and rolling the edges together. It will be observed that thisprocedure avoids all necessity of soldering or similar treatment, inview of the fact that the.

elasticity of the polymer material permits the easy production of atight seal between the various can members. Furthermore, the high heatresistance of the material permits of the sterilization of thecomestible within the container, after completing the sealing.

for solutions of caustic either diluted or concentrated. The polymermaterial is particularly useful as a liner for ducts conveying corrosivegases such as sulfur dioxide, sulfur trioxlde, hydrochloric acid gas andsimilar` corrosive vapors either in the presence or absence of moisture.

The material is particularlyV advantageous for containers to holdhydrochloric acid g'as, dissolved in water, which is exceedinglydiillcult to store in anything but glass and is rapidly contaminatedwith ferrie chloride when in contact with any ferrous materials. Thematerial is similarly advantageous as a liner for containers to holdacetic acid which also is dimcult to store and transport withoutcontamination. Similarly, the material is strongly resistant to causticsolutions and is particularly advantageous withstorage and handling ofconcentrated caustic solutions.

The material is advantageous as a covering for such articlesas acidbuckets and similar containers which may be formed of a metal base, andcovered on both inside and' outside with the sulfurized polymer. Themetal base may be pierced to allow a binding effect betweenlnner andouter coverings of the polymer and the material may be bound to themetal by an interposed illm of sulfurized polymer material deposited onthe metal structure. Such a structure is particularly advantageous inview of its high strength and flexibility and, even though it is bent orotherwise abusedand battered, breakage does not readily occur and thestructure may be repaired for further use.

The material similarly is highly advantageous for such uses as storagebattery cases, especially for automobile service where rubber has beenfound unsatisfactory. The frame ofthe battery case may be prepared as ametal form of any desired size and-shape, which is then covered insideand out with the sulfurized polymer substance. The resulting batterycase is highly advantageous for batteries used in automotive service,since it withstands the vibration and other abuse far better than anyprior type of case. The polymer is far more resistant toacid than issoft rubber and it is wholly lacking in the brittleness whichcharacterizes hard rubber, and, in addition, it .has an acid resistancewhich is superior to even the best hard rubber cases.

The material is further useful as a liner for blow cases or "acid eggssince it is strongly reporcelain vessels it is found to be amply strongto withstand the applied pressure.

Similarly, it is highly advantageous as a liner for autoclaves formoderate temperature service since the extreme chemical inertnesspermits of the handling oi' the very strongest of acids in such devices.

It is further highly advantageous as a liner for centrifugal pumps andas a covering for impellers. for the handling of acid and alkalinesolutions and for the handling of liquids which are corrosive because ofcontained solids which tend to erode the metal of the pump.

It is also particularly adapted as a protective coating on the exteriorof metallic structures. It is useful as a paint on ships' bottoms and itadheres strongly and provides long continued and thorough protectionagainst corrosion from salt water. By virtue of its plasticity, it isimpossible for marine growth to adhere. This nonadherence of marinegrowth can be still further promoted by incorporating into the polymercoating a layer of copper powder or copper pigment. Similarly. it isuseful as a protection for steel piling, especially in salt water andalso for wooden piling for which it provides valuable protection againstmarine growth and toredos.

It is also particularly adapted as a protective coating on the exteriorof metallic structures which are subject to corrosive gases or vapors.'I'he covering oi' polymer substance may be applied from solution, or inthe form of sheets oiv material which may be applied in the form asoriginally. compounded and then the maximum chemical resistancedeveloped by an appropriate heat treatment, or, the material may beheated in the sheet form to develop the maximum chemical resistance andthen the finished sheets applied to the structure and held in place by'an underlayer of material applied from solution.

The invention thus provides a metallic structure having a protectivecovering which is wholly resistant to the most powerful acid or alkalinecorrosive eiIects, and which at the same time has a high elasticity. ahigh abrasion resistance.4

a high resistance to vibration. and a powerful adhesive character to themetallic structure.

While there are above disclosed but a limited number of embodiments of'the invention, it is possible to produce still other embodiments withoutdeparting from the inventive concept herein disclosed, and it istherefore desired that only 5 such limitations be imposed upon theappended claims as are stated therein or required by the prior art.

The invention 'claimed is: Y 1. A structure comprisingV a metallic membeand an integral covering layer thereonpthe said layer comprising asolid. plastic, elastic, sulfurizable interpolymer of isobutyiene andbutadiene characterized by an elastic limit, a low iodine number and ahigh molecular weight and containing combined sulfur. Y

2. A tank structure comprising metallic memlbers constituting a tankstructure and an integral liner therein comprising 'a solid, plastic.elastic, sulfurizable interpolymer of isobutylene and butadienepolymerized together and characterized by an elastic limit, a low iodinenumber and a high molecular weight and compounded with sulfur.

3. A vcontainer comprising a metal form hav- 26 ing perforationstherein, and a complete covering for the said form comprising a polymerproduced from isobutylene and butadiene in the form of a solid, plastic,elastic, sulfurlzable interpolymer, characterized by a low iodine number30 and a high molecular weight and compounded with sulfur.

4. A container comprising a metal form having perforations therein, anda complete covering for the said form comprising a polymer produced fromisobutylene and butadiene in the form of a solid, plastic, elastic,sulfurizable interpolymer. characterized by a low iodine number and ahigh molecular weight and compounded with sulfur and inert nllers.

5. In a pressure-resistant container, a corrosion. pressureandtemperature-resistant lining comprising a solid. plastic, elastic.sulfurizable interpolymer of isobutylene-butadiene l characterized by alow iodine number and a high molecular weight compounded with combined

